Method for DC-DC conversion using a DC electric power source

1. A method for converting electricity provided by an energy source delivering a first direct voltage and a first direct current having first respective values into output electricity at a second direct voltage and a second direct current having second respective values, comprising: a) subjecting the first direct current to an inversion operation to form a third alternating current at a third voltage, said third current at said third voltage being mono- or polyphase, b) changing, through a conversion operation, the value of said third voltage, or the value of each phase thereof, to obtain at least one converted voltage having said second value while simultaneously, the current at said converted voltage is rectified in at least one conversion unit while being subjected to magnetic switching using a first and a second saturable induction coils, c) said saturable induction coils being connected in a serial rectifying current made up of said first saturable induction coil, a first and a second head-to-tail power diodes and the second of the saturable induction coils, the first and second head-to-tail power diodes being shunted by a first and a second head-to-tail regulating diodes with rectification directions opposite those of the first and second head-to-tail power diodes, d) said serial circuit being connected to receive said converted voltage and to deliver said electricity in the form of at least part of said second direct current, e) regulating, during each cycle of the converted voltage, the moments of the magnetic switching by injecting, through said regulating diodes, a control voltage created as a function of the variations of said second voltage, f) controlling, for a first portion of each of said cycles, under the effect of the saturation of said first saturable induction coil, the conduction of said first power diode, and controlling, for a second portion of each concerned cycle, under the effect of the saturation of said second saturable induction coil, the conduction of said second power diode, the saturation moments being determined during that cycle as a function of said control voltage, and g) during said first portion of said cycle, blocking said second power diode by conducting said first power diode, and during said second portion of the considered cycle, blocking said first power diode by conducting said second power diode, so as to create a phase shift between said third voltage and said third current or between the voltage and the current of each phase thereof, the phase shift angle depending on said control voltage, and in that the method steps b), e), f) and g) are carried out, if applicable, for each phase of said third voltage.

2. The conversion method according to claim 1 , further comprising smoothing said rectified current using at least one pair of smoothing induction coils in series connected on said converted voltage, said second voltage being taken from the node between said power diodes and the node between said smoothing induction coils of one pair.

3. A DC-DC converter for implementing the method according to claim 2 , wherein it includes an inverter, a conversion unit and a regulator, said conversion unit including a transducer comprising a primary connected to said inverter and a secondary whereof the ends are connected to a serial circuit made up of a first saturable induction coil, two head-to-tail power diodes and a second saturable induction coil, the two power diodes being shunted by two head-to-tail regulating diodes with rectification directions opposite those of the two power diodes, said conversion unit also including a second serial circuit formed from two smoothing induction coils and connected in parallel to said secondary of said transducer, said second voltage being taken between the shared node of said power diodes and the shared node of said smoothing induction coils, and said control voltage produced by said regulator being applied between the shared node of said regulating diodes and the shared node of said smoothing induction coils.

4. The DC-DC converter according to claim 3 , wherein said smoothing induction coils include a shared magnetic circuit on which their respective windings are wound, said magnetic circuit having an air gap associated in common with the two smoothing induction coils, said windings having a low coupling with one another ensured only through said magnetic circuit, the winding direction of the two windings being such that the flows they create in the magnetic circuit and which are due to the direct current components, pass through said air gap in the same direction.

5. The DC-DC converter according to claim 4 , wherein the windings of said smoothing induction coils also make up the secondaries of said transducer, and in that each of these windings is wound together on said magnetic circuit tightly, with half of a winding of said transducer, said two winding halves forming the primary thereof.

6. The DC-DC converter according to claim 4 , wherein said magnetic circuit is ring-shaped.

7. An electricity distribution facility, in particular for satellites, wherein it includes a plurality of converters according to claim 3 , said inverter being shared by all of the converters.

8. An electricity distribution facility, in particular for satellites, wherein it includes at least one converter according to claim 3 , built with a plurality of conversion units powered by a shared transducer, including a plurality of secondaries at a rate of one per unit.

9. The electricity distribution facility according to claim 8 , wherein each of said conversion units is provided with its own regulator.

10. An electricity distribution facility, in particular for satellites, wherein, it includes at least one converter according to claim 3 built with a plurality of conversion units arranged in at least one group of conversion units powered by means of a shared transducer connected by its primary to said inverter and including as many secondaries as there are conversion units in a group, in that one of said conversion units of a group being able to be a pilot conversion unit formed by a mono-alternation rectifier with no phase shift means, in that said inverter is adjustable, in that the facility includes an adjustment loop acting on said inverter to adjust it as a function of the difference signal between a voltage reference signal and a signal depending on the output voltage of said pilot conversion unit, and in that the other conversion units of a group then being provided with their own regulator.

11. An electricity distribution facility, in particular for satellites, designed to implement the method according to claim 2 , wherein it includes a polyphase inverter, a plurality of conversion units, said conversion units being distributed in at least one group of at least three units, and, associated with each group, a regulator for performing said regulating operation, in that for performing said conversion operation of said third voltage, the conversion units of one group of units are associated with a shared transducer with a polyphase primary and having as many secondaries as there are conversion units in the group, this transducer being connected to said inverter by means of a multi-line cable, in that said regulator applies the same control voltage to the units of a group, and in that in a group of conversion units, the outputs thereof are connected in parallel to provide, on two output terminals of that group, the sum of their individual output currents as second output current.

12. The electricity distribution facility, in particular for satellites, according to claim 11 , wherein the smoothing induction coils belonging to the conversion units of a same group of conversion units can advantageously be grouped together on a shared magnetic circuit on which their respective windings are wound, this magnetic circuit having a single air gap, the coupling of these windings to one another being ensured only through said shared magnetic circuit, the winding direction of said windings being such that the flows due to the direct current components that pass through these windings pass through said air gap in the same direction.

13. The electricity distribution facility, in particular for satellites, according to claim 12 , wherein in each group of conversion units, the smoothing induction coils grouped together on said shared magnetic circuit can respectively also serve as secondaries of said single transducer whereof the primary windings are respectively divided into two half-windings each coupled to one of the secondary windings also serving as smoothing induction coils for the conversion unit to which they are connected.

14. The conversion method according to claim 1 , further comprising determining said control voltage as a function of said at least one portion of the second current.

15. The conversion method according to claim 14 , wherein said control voltage is determined as a function of an image of said second current taken either from the filtered average of two voltages respectively taken between the terminals of said saturable induction coils opposite the terminals that are connected to said power diodes, and a reference point shared by the second voltage and said control voltage, in the monophase case, or from the set of filtered averages of these voltages in all of the phases, in the polyphase case.

16. The conversion method according to claim 14 , wherein the determination of said control voltage is done from an image of said second current of form Vc/k-Vs, Vc being said third voltage, k being a constant comprised between 1 and 3.

17. A DC-DC converter for implementing the method according to claim 14 , wherein it includes an inverter, a conversion unit and a regulator, said conversion unit including a transducer comprising a primary connected to said inverter and a secondary whereof the ends are connected to a first serial circuit made up of a first saturable induction coil, two head-to-tail power diodes and a second saturable induction coil, the two power diodes being shunted by two head-to-tail regulating diodes with rectification directions opposite those of the two power diodes, the secondary of said transducer being made up of two half-windings that have a weak magnetic coupling between them and which are coupled, preferably strongly, respectively each to half of the primary winding of said transducer, in return for which said half-windings respectively serve both as half-secondary for the conversion and smoothing induction coil, said second voltage being taken between the shared node of said power diodes and the shared node of said half-windings of said transducer, and said control voltage produced by said regulator being applied between the shared node of said regulating diodes and the shared node between said power diodes.

18. The DC-DC converter according to claim 17 , wherein the primary of said transducer is wound on two distinct elementary magnetic circuits to form said two primary half-windings connected in series, each of these half-windings being strongly coupled together with a respective half-winding of the secondary of the transducer on an elementary magnetic circuit.

19. The DC-DC converter according to claim 18 , wherein each of said elementary magnetic circuits is made in the shape of a C thereby forming an air gap, or in the form of a toroid.

20. A DC-DC converter for implementing the method according to claim 14 , wherein it includes an inverter, a conversion unit and a regulator, said conversion unit including a transducer comprising a primary connected to said inverter and made up of two primary half-windings connected in series and a secondary made up of two half-windings also connected in series, the half-windings of the primary respectively forming, with the half-windings of the secondary, pairs each made up of a primary half-winding and a secondary half-winding that are closely coupled to one another, said primary being connected to said inverter and said secondary being connected to a serial circuit made up of a first saturable induction coil, two head-to-tail power diodes and a second saturable induction coil, the two power diodes being shunted by two head-to-tail regulating diodes with rectification directions opposite those of the two power diodes, said converter also including a single smoothing induction coil connected between the shared node of said secondary half-windings and an output terminal of said conversion unit supporting the negative potential of said second voltage, the output terminal of said unit supporting the positive potential thereof being connected to the shared node of said power diodes, and said control voltage produced by said regulator being applied between the shared node of said regulating diodes and said output terminal of the conversion unit supporting said negative potential.

21. The DC-DC converter according to claim 20 , wherein said transducer includes a magnetic circuit on which two distinct sets of half-windings are wound, these sets being located in different places on said magnetic circuit and each made up of a primary half-winding and a secondary half-winding, the half-windings of each set being wound with a tight coupling.

22. The converter according to claim 20 , wherein said single induction coil includes a ring-shaped magnetic circuit.

23. The conversion method according to claim 1 , wherein said control voltage is referenced related to the positive potential of said second voltage.

24. The conversion method according to claim 1 , wherein said control voltage is referenced related to the negative potential of said second voltage.

25. An electricity distribution facility, in particular for satellites, designed to implement the method according to claim 1 , wherein it includes a polyphase inverter, a plurality of conversion units, said conversion units being distributed in at least one group of at least three units and, associated with each group, a regulator to perform said regulation operation, in that each conversion unit of a group of units includes a transducer to perform said conversion operation of said third voltage, the transducers of the units of a group being connected to said inverter by means of a multi-line cable, in that said regulator applies the same control voltage to the units of a group, and in that in a group of conversion units, the outlets thereof are connected in parallel to provide, on two output terminals of that group, the sum of their individual output currents as second output current.

26. The electricity distribution facility according to claim 25 , wherein in each of said groups of conversion units, they can be connected in a triangle or star to said inverter.